Historians still split in their opinions over the events, which took place on September 28, 1939. That day, 71 years ago, the USSR and Hitler’s Germany signed the Boundary and Friendship Treaty, which marked the logic ending of the previously concluded Non-Aggression Pact.The treaty was signed by foreign ministers of the two countries – Vyacheslav Molotov and Joachim von Ribbentrop.The official protocol of the treaty regulated the procedure to exchange Soviet and German citizens between two parts of the divided Poland. The document also defined new borders between the USSR and Germany.However, the treaty had two other secret protocols. They corrected the zones of East European spheres of interests. Lithuania, for example, was handed over to the sphere of interests of the Soviet Union, whereas a big part of the Polish territory was passed from the Soviet Union to Germany. The document also set the obligation of the parties to cease any “Polish agitation” that touched upon the interests of the treaty members.